From ce88ac66c50307744d7d431cf12e4d79fede56f2 Mon Sep 17 00:00:00 2001
From: Alisina Bahadori <alisina.bm@gmail.com>
Date: Sat, 7 Dec 2024 21:11:41 -0500
Subject: [PATCH] Add `Ethers.chain_id/1`

---
 lib/ethers.ex             | 10 +++++++++-
 lib/ethers/transaction.ex |  4 ++++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/lib/ethers.ex b/lib/ethers.ex
index 462b57e..90ec6d1 100644
--- a/lib/ethers.ex
+++ b/lib/ethers.ex
@@ -70,6 +70,7 @@ defmodule Ethers do
 
   @option_keys [:rpc_client, :rpc_opts, :signer, :signer_opts, :tx_type]
   @hex_decode_post_process [
+    :chain_id,
     :current_block_number,
     :current_gas_price,
     :estimate_gas,
@@ -95,6 +96,13 @@ defmodule Ethers do
 
   defguardp valid_result(bin) when bin != "0x"
 
+  def chain_id(opts \\ []) do
+    {rpc_client, rpc_opts} = get_rpc_client(opts)
+
+    rpc_client.eth_chain_id(rpc_opts)
+    |> post_process(nil, :chain_id)
+  end
+
   @doc """
   Returns the current gas price from the RPC API
   """
@@ -733,7 +741,7 @@ defmodule Ethers do
     case errors_module.find_and_decode(error_data) do
       {:ok, error} -> {:error, error}
       {:error, :undefined_error} -> {:error, full_error}
-      e -> e
+      {:error, reason} -> {:error, reason}
     end
   end
 
diff --git a/lib/ethers/transaction.ex b/lib/ethers/transaction.ex
index 375a9b1..79e5ed6 100644
--- a/lib/ethers/transaction.ex
+++ b/lib/ethers/transaction.ex
@@ -242,6 +242,10 @@ defmodule Ethers.Transaction do
     end
   end
 
+  defp do_post_process(:chain_id, {:ok, v_int}) when is_integer(v_int) do
+    {:ok, {:chain_id, Utils.integer_to_hex(v_int)}}
+  end
+
   defp do_post_process(:max_fee_per_gas, {:ok, v_hex}) do
     with {:ok, v} <- Utils.hex_to_integer(v_hex) do
       # Setting a higher value for max_fee_per gas since the actual base fee is